Method for removing selenium from tellurium ingot

Abstract

The invention discloses a method for removing selenium from a tellurium ingot, which comprises the following steps: (1) in a hydrogen atmosphere, heating and melting the tellurium ingot, and controlling the temperature of tellurium melt to remove selenium, wherein the temperature control process comprises the following three stages: i) controlling the temperature at 500-520 DEG C in the first stage, ii) controlling the temperature to be 530-550 DEG C in the second stage, and iii) controlling the temperature at 560-600 DEG C in a third stage; and (2) conducting a cooling process, namely keeping the hydrogen atmosphere, and conducting cooling to obtain the high-purity tellurium material. According to the method, the tellurium ingot is subjected to selenium removal in a three-section accurate temperature control treatment mode, the selenium removal process is effectively controlled, the selenium removal efficiency is high, the period is short, selenium removal is thorough, the tellurium loss is small, impurities such as Pb, Bi, Na and Si in the tellurium material can be reduced to 1 ppm or below, impurities such as Cu, Mg and As can be reduced to 0.5 ppm or below, the impurity selenium difficult to remove can be reduced to 2 ppm or below, and the prepared 5N tellurium ingot can be used in the fields of solar cells, LEDs, thermoelectricity, infrared and other semiconductor materials.

Description

technical field [0001] The invention belongs to the field of tellurium ingot purification, in particular to a method for deselenium from tellurium ingot. Background technique [0002] Tellurium is an oxygen group element with an atomic number of 52. It is located between selenium and polonium in the main group VI of the fifth cycle, and has obvious metallic properties. The main impurity elements in tellurium ingots are Se, Pb, As, Na, Mg, Bi, Cu, etc., among which the most difficult element to remove is Se. Selenium and tellurium belong to the same main group with similar properties, and selenium is an associated element of tellurium, so 4N tellurium materials often contain high impurity element selenium, reaching tens or even tens of ppm, because the physical and chemical properties of the two have great differences Similarly, it is difficult to directly reduce selenium to a lower level by general chemical or physical purification methods, which limits the development of t...

AI Technical Summary

Problems solved by technology

Selenium and tellurium belong to the same main group with similar properties, and selenium is an associated element of tellurium, so 4N tellurium materials often contain high impurity element selenium, reaching tens or even tens of ppm, because the physical and chemical properties of the two have great differences Similarity, it is difficult to directly reduce selenium to a lower level by general chemical or physical purification methods, which limits the development of tellurium purification technology

[0003] Conventional tellurium ingot deselenization methods mainly include vacuum distillation, regional smelting, chemical purification, etc. In the production process of regional smelting, the smelting temperature is high, energy consumption is high, the number of cycles is high, the production cycle is long, and the efficiency is low, and Selenium is difficult to separate and deselenium is not complete; although selenium is easier to volatilize into the gas phase than tellurium by vacuum distillation, the method of vacuum distillation cannot effectively remove selenium in tellurium, deselenium is unstable and incomplete, and the deselenium efficiency Low; it is difficult to purify tellurium to 5N by pure chemical method, and it is even more difficult to reduce the content of selenium to less than 10ppm, which needs to be realized in combination with other physical methods

[0004] Chinese patent CN107585745A discloses a preparation method of 5N tellurium. This technology needs to pre-treat tellurium to meet the national standard 4N standard before production, reduce the content of some impurities in the raw material through screening or pre-treatment, and then carry out vacuum distillation purification. The treatment effect of selenium is not good, the treatment cycle is long, the deselenium efficiency is low, and the deselenium is not complete

Chinese patent CN110894065A discloses an equipment and method for preparing high-purity tellurium. The method is used to produce 6N high-purity tellurium. The technology includes a vacuum distillation device, a vacuum device, a hydrogen purification cycle device, a high-frequency induction heating device and product collection. Devices, etc. The combination of technical equipment is complex, and the operation difficulty coefficient is relatively high, which is not conducive to industrial production

This technical solution has a long selenium removal period and incomplete removal

Chinese patent CN106517106A discloses a high-efficiency purification method for high-purity tellurium. This invention firstly purifies tellurium to 3N-4N refined tellurium by chemical method, and then melts the obtained refined tellurium at 400-700°C in a hydrogen atmosphere. , using the Czochralski purification method to obtain 5N-6N tellurium, because tellurium has certain non-metallic properties, and the crystallization properties of tellurium are not good, so the effect of removing impurities in the pulling process is general, and the properties of selenium and tellurium are similar. The effect of deselination is poor, and the amount of waste liquid is large

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